The present invention relates to a method of influencing driving dynamics parameters.
A method of this type is disclosed in WO-A 86/07321. This publication refers to adjusting a brake slip value during controlled braking of a vehicle wheel where the coefficient of friction Ti in the longitudinal direction is close to the maximum attainable value, on the one hand, and a sufficient coefficient of friction in the transverse direction is available, on the other hand. This slip value is below the value at which the coefficient of friction in the longitudinal direction is at its maximum. While the frictional value/brake slip curve .lambda.(.mu.) has the gradient 0 at the maximum coefficient of friction in the longitudinal direction, .lambda.(.mu.) adopts positive gradients at the slip value to be adjusted. Beside the advantage of higher cornering forces, the prior art concept provides the possibility of definedly limiting yaw torques occurring on the vehicle during controlled braking and, thus, improving the ability to govern the vehicle. To this end, gradient values on the frictional value-slip curve are aimed at in brake pressure control, which are e.g. made responsive to the steering angle or other actual driving conditions. The precondition for this control is that the wheel sensors for ascertaining the individual rotational speeds are in a state of operation. In a road vehicle equipped with four wheel sensors, it cannot be expected that all four wheel sensors stay intact for the total useful life of the vehicle. Upon failure of a wheel sensor, however, a control of the above type is not possible because the brake slip of the respective wheel cannot be ascertained. Usually, brake slip control is disconnected in such cases.
An object of the present invention is to provide a method of the type mentioned hereinabove which provides sort of an emergency function for the control even if at least one wheel sensor is defective.